Atomic core-polarization effects in metastable hadronic helium atoms

A theoretical consideration is presented concerning the atomic core-polarization effect on the E1 transitions of large-l circular orbitals in hadronic helium atoms (e^-{X}^{{{-}}}He²⁺), where the e^- occupies the 1s orbital and the negative hadron (X^-) occupies a large-l circular orbital. The first-order mixing of the 2p electron configuration due to the repulsive e^--{X}^{{{-}}}interaction gives rise to a substantial suppression (~1/3) of the E1 transitions, compared with a single-particle estimate, since the slowly moving particle ({X}^{{{-}}}$) polarizes the electron cloud in the opposite direction. Recently discovered metastable states of antiprotonic helium atoms are discussed.